AP Chemistry:: Thermodynamics

What is THERMODYNAMICS, as a general area of study within chemistry?

- **A)** Thermodynamics is concerned exclusively with a reaction's overall MECHANISM, rather than its energy changes
- **B)** This area of study has no actual relationship to energy changes accompanying chemical or physical processes
- **C)** Thermodynamics refers only to the RATE at which a reaction occurs, with no relationship to energy changes
- **D)** The study of ENERGY changes (particularly heat) that accompany chemical reactions and physical processes

What is the SYSTEM and the SURROUNDINGS, as basic thermodynamic terms used to describe energy transfer during a process?

- **A)** The system and surroundings always refer to the exact SAME single region, with no meaningful distinction between them
- **B)** The system refers to EVERYTHING in the universe, while the surroundings refers to a small, specific part being studied (the reverse of the actual definitions)
- **C)** The SYSTEM is the specific part of the universe being studied (e.g., the reacting chemicals), while the SURROUNDINGS is EVERYTHING ELSE outside the system that could exchange energy with it
- **D)** This distinction has no actual relationship to describing where energy transfer occurs during a thermodynamic process

What is an EXOTHERMIC process, and in which direction does HEAT flow between the system and surroundings during such a process?

- **A)** This concept has no actual relationship to the direction heat flows between a system and its surroundings
- **B)** A process that RELEASES heat energy FROM the system INTO the surroundings -- the surroundings typically become WARMER as a result
- **C)** An exothermic process ABSORBS heat energy FROM the surroundings INTO the system, the reverse of the actual direction of heat flow
- **D)** Exothermic processes never actually involve any transfer of heat energy between the system and surroundings

What is an ENDOTHERMIC process, and how does it CONTRAST with an EXOTHERMIC process in terms of heat flow direction?

- **A)** A process that ABSORBS heat energy FROM the surroundings INTO the system -- the surroundings typically become COOLER as a result, the OPPOSITE heat-flow direction of an exothermic process
- **B)** Endothermic processes always cause the surroundings to become WARMER, identical to the effect of an exothermic process
- **C)** This concept has no actual relationship to heat flowing from the surroundings into the system
- **D)** An endothermic process releases heat FROM the system INTO the surroundings, identical to an exothermic process with no meaningful distinction

What is ENTHALPY (H), and what does a NEGATIVE change in enthalpy (delta H < 0) indicate about a reaction?

- **A)** Enthalpy change is always POSITIVE for every possible chemical reaction, with negative values being physically impossible
- **B)** Enthalpy has no actual relationship to whether a reaction releases or absorbs heat
- **C)** A negative delta H indicates the reaction is ENDOTHERMIC, the reverse of the actual relationship between enthalpy change sign and reaction type
- **D)** A thermodynamic property related to the HEAT content of a system at constant pressure; a NEGATIVE delta H indicates the reaction is EXOTHERMIC (releases heat, products have lower enthalpy than reactants)

What is CALORIMETRY, as an experimental technique, and what does it allow a chemist to MEASURE about a chemical or physical process?

- **A)** Calorimetry can only be used to measure a substance's MASS, rather than heat energy transfer
- **B)** Calorimetry refers only to measuring a reaction's RATE, with no relationship to measuring heat energy transfer
- **C)** An experimental technique used to MEASURE the amount of HEAT ENERGY released or absorbed during a chemical reaction or physical process, typically by tracking a TEMPERATURE change in a surrounding medium (like water)
- **D)** This technique has no actual relationship to measuring heat energy released or absorbed during a process

What is SPECIFIC HEAT CAPACITY, and how does it relate to how much a substance's TEMPERATURE changes when it absorbs a given amount of heat energy?

- **A)** This concept has no actual relationship to how much heat energy is needed to change a substance's temperature
- **B)** A substance with a HIGH specific heat capacity requires LESS energy to change its temperature than a substance with a LOW specific heat capacity (the reverse of the actual relationship)
- **C)** Specific heat capacity refers to a substance's total MASS, with no relationship to how much its temperature changes when it absorbs heat
- **D)** The amount of heat energy required to raise the temperature of ONE GRAM of a substance by ONE DEGREE CELSIUS; a substance with a HIGH specific heat capacity requires MORE energy to achieve the same temperature change compared to a substance with a LOW specific heat capacity

What is the mathematical equation q = mc(delta T), commonly used in calorimetry calculations, and what does EACH variable in this equation represent?

- **A)** This equation has no actual relationship to calculating heat energy transfer based on mass, specific heat capacity, and temperature change
- **B)** 'q' in this equation represents a substance's MASS, while 'm' represents the heat energy transferred (the reverse of the actual variable assignments)
- **C)** 'q' represents the HEAT energy transferred, 'm' represents the MASS of the substance, 'c' represents its SPECIFIC HEAT CAPACITY, and 'delta T' represents the CHANGE IN TEMPERATURE the substance undergoes
- **D)** 'delta T' in this equation always represents a substance's specific heat capacity, rather than its temperature change